RF amplifiers typically include bias circuitry configured to provide DC bias voltages to the amplifier transistor(s). To ensure that a significant amount of RF power is not lost through the bias circuitry, it is important to de-couple or isolate the RF circuitry from the DC bias circuitry. Isolation may be achieved, for example, by including a quarter wave (lambda/4) transmission line in the DC bias transmission line, with a reactive component at the end of the quarter wave line that resonates at the fundamental frequency of the RF circuitry. Ideally, using this configuration, the bias line emulates infinite impedance at frequencies near the fundamental frequency, thus isolating the bias circuitry at those frequencies. However, the characteristic impedance of the bias line limits the bandwidth of frequencies for which effective isolation may be achieved.